1. Field of the Disclosure
Embodiments disclosed herein relate generally to oilfield shakers. More particularly, embodiments disclosed herein relate to apparatus and methods for pre-tensioned screens for oilfield shakers.
2. Background Art
Oilfield drilling fluid, often called “mud,” serves multiple purposes in the industry. Among its many functions, the drilling mud acts as a lubricant to cool rotary drill bits and facilitate faster cutting rates. Typically, the mud is mixed at the surface and pumped downhole at high pressure to the drill bit through a bore of the drillstring. Once the mud reaches the drill bit, it exits through various nozzles and ports where it lubricates and cools the drill bit. After exiting through the nozzles, the “spent” fluid returns to the surface through an annulus formed between the drillstring and the drilled wellbore.
One significant purpose of the drilling mud is to carry the cuttings away from the drill bit at the bottom of the borehole to the surface. As a drill bit pulverizes or scrapes the rock formation at the bottom of the borehole, small pieces of solid material are left behind. The drilling fluid exiting the nozzles at the bit acts to stir-up and carry the solid particles of rock and formation to the surface within the annulus between the drillstring and the borehole. Therefore, the fluid exiting the borehole from the annulus is a slurry of formation cuttings in drilling mud. Before the mud can be recycled and re-pumped down through nozzles of the drill bit, the cutting particulates must be removed.
Apparatus in use today to remove cuttings and other solid particulates from drilling mud are commonly referred to in the industry as “shale shakers.” A typical shaker is shown in FIG. 1. In typical shakers, a screen 102 is detachably secured to the vibrating shaker machine 100. With the screen or multiple screens secured in place, a tray is formed with the opposed, parallel sidewalls 103 of shaker 100. The drilling mud, along with drill cuttings and debris, is deposited on top of screen 102 at one side. Screen 102 is vibrated at a high frequency or oscillation by a motor or motors for the purpose of screening or separating materials placed on screen 102. The liquid and fine particles will pass through screen 102 by force of gravity and be recovered underneath. Solid particles above a certain size migrate and vibrate across screen 102 or screens where they are removed. Filtering elements attached to screen 102 may further define the largest solid particle capable of passing therethrough.
Due to the conventional design of and installation methods for pre-tensioned screens, sealing between the screen frame and shaker bed may be insufficient to prevent drilling fluid from bypassing the screen frame and/or filtering element. Accordingly, there exists a need for a shaker screen without excessive bowing.